1. Field of the invention
This invention relates to a load tie-down or securement system and, more particularly, to an improved log haulers securement system which can be used to better secure non-uniform, abrasive loads such as logs, for transport via a trailer.
2. Description of the prior art
There is an acute need in the log-hauling industry for an improved system of securing loads of logs onto trailers for transport from the forests where such logs are first cut from live trees to the mills where the logs are processed into lumber or other related forestry products.
A load of logs typically consists of individual logs which are, within certain limits, non-uniform in diameter and in length. Unlike most manufactured items, a load of logs usually includes individual logs having diameters which are larger at one end than at the other. Furthermore, each individual log is itself non-uniform, apart from the lower portions of the log being larger than the upper portions. Most logs feature larger diameters at locations along the log where branches were formerly attached.
In addition to the non-uniformity, logs are also relatively abrasive, making it impractical to use standard webbing or strapping binding materials to secure such loads. Webbing or other straps of woven or braided material is widely used in the transportation industry for securing loads which are more uniform and less abrasive than logs. Examples of a few such applications can be found in U.S. Pat. Nos. 2,442,266, 2,623,760, 2,679,670, 2,998,625, 3,377,044, 4,054,267, 4,243,350 and 4,297,062.
Because logs tend to be highly abrasive, the predominant binding material in the log hauling industry has for years been chains and in some cases cables, or a combination of chain and cable, known as wire rope. Examples of the use of cables can be seen in U.S. Pat. Nos. 2,991,975 and 3,077,791, and in U.S. Pat. No. Re. 30,307.
The vast majority of log trucks currently use chains to secure the load. One or more chains is first thrown over the load. A boomer, or load binder, which is essentially a lever device, is then used to tightly pull the chain ends to a position where the chain is firmly grasping the load of logs.
Because of the lack of uniformity of logs, and because of their large weight, loads of logs tend to shift and settle during transport from the forest to the mill. When shifting or settling occurs, the chain is often loosened, typically by four inches or more. This loosening of the chain can often cause the boomer, or load binder, to become loose and allow the two ends of the chain to completely detach from the boomer, or load binder, causing the chain and/or the load binder to fall off the load. This leaves the load of logs unsecured and can lead to the loss of some or all of the logs onto the roadway.
The loss of a load of logs leads to large economic penalties. Even more importantly, logs falling off a trailer onto the roadway severely threatens the safety of the motoring public sharing the public roads with the log trucks.
The recurrent problems associated with a partial loss of loads of logs from trailers has created an urgent need for more effective systems for securely binding loads of logs onto trailers for transportation from the forests to the mills.
The prevalent technique is the chain and load binder method described above. Attempts have been made to overcome the shortcomings inherent in that system described above. Several methods use a cable instead of a chain. Use of a cable makes it possible to use a winch mechanism for easier tightening. Typical of such system are those described in U.S. Pat. Nos. 2,991,975 and 3,077,791, and U.S. Pat. No. Re. 30,307. These references all disclose similar methods which employ a special winch for automatically taking up at least some of the slack in the cable created when the logs settle during transport.
While this type of mechanism appears to be an improvement over the chain and load binder system, it is largely inadequate. In particular, it would appear that the amount of slack cable which can automatically be taken up is insufficient to tighten the cable. In addition, the devices disclosed would be incapable of exerting sufficient force to adequately tighten a cable which has become slack around a load of heavy logs. These deficiencies may explain why such devices have not been used commercially in the log transportation industry.
A shortcoming of the presently widely used system of securement using a chain and load binder is that the chain is susceptible to loosening and falling off the load, making it easier for the load, as well as the boomer and chain, to fall off the truck and endanger the safety of motorists. Attempts to improve this system with the use of cables and winches capable of automatically tightening the slackened cable have to date been commercially unsuccessful.
It would thus be desirable to have a securement system for use in tying down loads which are non-uniform and abrasive, such as logs, which (1) would eliminate the use of chains and load binders which are prone to loosening and falling off the load, (2) would securely bind a load of logs and continue to contain the load even after the load has shifted or settled, (3) would be easy to use, and (4) would readily facilitate retightening to take up slack created upon settling of the load. A clear need exists in the industry for such a safe and convenient securement system.